1. Field of the Invention
The present invention relates to a cardboard sheet batch division device, and in particular to a cardboard sheet batch division device for dividing into batches of a predetermined number of sheets and transferring cardboard sheets which have been bent and glued after such processing as printing.
2. Description of the Related Art
A cardboard sheet box-making machine comprising: a folder-gluer for folding and gluing with glue a printed or otherwise processed cardboard sheet, and a counter ejector for counting the cardboard sheets supplied from the folder-gluer, forming a batch of a predetermined number of cardboard sheets, and sending this batch to a follow-on bundler. Cardboard sheet box-making machines of this type are disclosed in JP-A-2009-51024 (having a counterpart US2010/0190626A) and JP-B-3298896 (having a counterpart U.S. Pat. No. 6,129,503A), and are well known.
The counter ejector disclosed in JP-A-2009-51024 comprises: a hopper on which cardboard sheets supplied from a folder-gluer are loaded; multiple ledges for separating cardboard sheets loaded in the hopper to form batches of a predetermined number of sheets; an elevator for raising those batches for loading; and a press bar for pressing the batches onto the loading surface of the elevator. The elevator descends from an upper position as the elevator loads the batch formed by the horizontal and vertical movement of the multiple ledges, handing the batch over to a lower conveyor for transfer at a lower position. After this handover is completed, the elevator rises to an upper position to load the next batch. The elevator repeats the raising and lower motion in the vertical direction to hand over each batch. The press bar descends as the press bar presses the batch onto the elevator loading surface during the interval when the elevator is descending from an upper position to a lower position. Through the pushing action of the press bar, the batch is handed over to the lower conveyor without becoming unbalanced on the downward path, and glued portions of each cardboard sheet in the batch are made to more strongly adhere.
In recent years, the need has arisen to process at high speed a wide variety of cardboard sheets using cardboard sheet box-making machinery, and to form small-lot batches with small cardboard sheet counts. To respond to this need, the speed of operation of various constituent parts such as the multiple ledges and elevators in a counter-ejector, has been increased. With respect to multiple ledges, for example, horizontal and vertical movements are implemented at high speeds to separate cardboard sheets supplied from a folder-gluer, and to form small-lot batches at high speed. The elevator and press bar also perform the raising and lowering motion at high speed to hand over each batch.
However, when forming small-lot batches at high speed, the batches are formed by multiple ledges and transported downward by the elevator before the ends of the cardboard sheets supplied from the folder-gluer are sufficiently aligned within the hopper, so it may occur that small-lot batches are formed with cardboard sheet edges in a misaligned state. A certain time is also needed for gluing until the glued portions of the cardboard sheet reach sufficient strength, but it can occur that before this certain time elapses, a batch is handed over from the hopper to a downstream conveyor, and opposing forces act on the top surface and bottom surface of the batch when this handover occurs, offsetting the glued portions. As a result, the problem arises that the quality of the external appearance of a small-lot batch, as well as the manufacturing quality of the cardboard sheet, degrades as speed is increased.